A liver metalloendopeptidase which degrades the circulating hypotensive peptide hormones bradykinin and atrial natriuretic peptide

A new metalloendopeptidase was purified to apparent homogeneity from a homogenate of normal human liver using successive steps of chromatography on DEAE-cellulose, hydroxyapatite and Sephacryl S-200. The purified enzyme hydrolyzed the Pro7-Phe8 bond of bradykinin and the Ser25-Tyr26 bond of atrial natriuretic peptide. No cleavage was produced in other peptide hormones such as vasopressin, oxytocin or Met- and Leu-enkephalin. This enzyme activity was inhibited by 1 mM divalent cation chelators such as EDTA, EGTA and o-phenanthroline and was insensitive to 1 µM phosphoramidon and captopril, specific inhibitors of neutral endopeptidase (EC 3.4.24.11) and angiotensin-converting enzyme (EC 3.4.15.1), respectively. With Mr 85 kDa, the enzyme exhibits optimal activity at pH 7.5. The high affinity of this endopeptidase for bradykinin (Km = 10 µM) and for atrial natriuretic peptide (Km = 5 µM) suggests that it may play a physiological role in the inactivation of these circulating hypotensive peptide hormones.

Purification and partial characterization of Phaseolus vulgaris seed aminopeptidase

The aminopeptidase activity of Phaseolus vulgaris seeds was measured using L-Leu-p-nitroanilide and the L-aminoacyl-ß-naphthylamides of Leu, Ala, Arg and Met. A single peak of aminopeptidase activity on Leu-ß-naphthylamide was eluted at 750 µS after gradient elution chromatography on DEAE-cellulose of the supernatant of a crude seed extract. The effluent containing enzyme activity was applied to a Superdex 200 column and only one peak of aminopeptidase activity was obtained. SDS-polyacrylamide gel electrophoresis (10%) presented only one protein band with molecular mass of 31 kDa under reducing and nonreducing conditions. The aminopeptidase has an optimum pH of 7.0 for activity on all substrates tested and the highest Vmax/KM ratio for L-Leu-ß-naphthylamide. The enzyme activity was increased 40% by 0.15 M NaCl, inhibited 94% by 2.0 mM Zn2+, inhibited 91% by sodium p-hydroxymercuribenzoate and inhibited 45% by 0.7 mM o-phenanthroline and 30 µM EDTA. Mercaptoethanol (3.3 mM), dithioerythritol (1.7 mM), Ala, Arg, Leu and Met (70 µM), p-nitroaniline (0.25 mM) and ß-naphthylamine (0.53 mM) had no effect on enzyme activity when assayed with 0.56 mM of substrate. Bestatin (20 µM) inhibited 18% the enzyme activity. The aminopeptidase activity in the seeds decayed 50% after two months when stored at 4oC and room temperature. The enzyme is leucyl aminopeptidase metal- and thiol group-dependent.

CPU0213, a novel endothelin type A and type B receptor antagonist, protects against myocardial ischemia/reperfusion injury in rats

The efficacy of endothelin receptor antagonists in protecting against myocardial ischemia/reperfusion (I/R) injury is controversial, and the mechanisms remain unclear. The aim of this study was to investigate the effects of CPU0123, a novel endothelin type A and type B receptor antagonist, on myocardial I/R injury and to explore the mechanisms involved. Male Sprague-Dawley rats weighing 200-250 g were randomized to three groups (6-7 per group): group 1, Sham; group 2, I/R + vehicle. Rats were subjected to in vivo myocardial I/R injury by ligation of the left anterior descending coronary artery and 0.5% sodium carboxymethyl cellulose (1 mL/kg) was injected intraperitoneally immediately prior to coronary occlusion. Group 3, I/R + CPU0213. Rats were subjected to identical surgical procedures and CPU0213 (30 mg/kg) was injected intraperitoneally immediately prior to coronary occlusion. Infarct size, cardiac function and biochemical changes were measured. CPU0213 pretreatment reduced infarct size as a percentage of the ischemic area by 44.5% (I/R + vehicle: 61.3 ± 3.2 vs I/R + CPU0213: 34.0 ± 5.5%, P < 0.05) and improved ejection fraction by 17.2% (I/R + vehicle: 58.4 ± 2.8 vs I/R + CPU0213: 68.5 ± 2.2%, P < 0.05) compared to vehicle-treated animals. This protection was associated with inhibition of myocardial inflammation and oxidative stress. Moreover, reduction in Akt (protein kinase B) and endothelial nitric oxide synthase (eNOS) phosphorylation induced by myocardial I/R injury was limited by CPU0213 (P < 0.05). These data suggest that CPU0123, a non-selective antagonist, has protective effects against myocardial I/R injury in rats, which may be related to the Akt/eNOS pathway.

Cell wall polysaccharides of common beans (Phaseolus vulgaris L.)

The soluble and insoluble cotyledon (SPF-Co and IPF-Co) and tegument (SPF-Te and IPF-Te) cell wall polymer fractions of common beans (Phaseolus vulgaris) were isolated using a chemical-enzymatic method. The sugar composition showed that SPF-Co was constituted of 38.6% arabinose, 23.4% uronic acids, 12.7% galactose, 11.2% xylose, 6.4% mannose and 6.1% glucose, probably derived from slightly branched and weakly bound polymers. The IPF-Co was fractionated with chelating agent (CDTA) and with increasing concentrations of NaOH. The bulk of the cell wall polymers (29.4%) were extracted with 4.0M NaOH and this fraction contained mainly arabinose (55.0%), uronic acid (18.9%), glucose (10.7%), xylose (10.3%) and galactose (3.4%). About 8.7% and 10.6% of the polymers were solubilised with CDTA and 0.01M NaOH respectively and were constituted of arabinose (52.0 and 45.9%), uronic acids (25.8 and 29.8%), xylose (9.6 and 10.2%), galactose (6.1 and 3.9%) and glucose (6.5 and 3.8%). The cell wall polymers were also constituted of small amounts (5.6 and 7.2%) of cellulose (CEL) and of non-extractable cell wall polymers (NECW). About 16.8% and 17.2% of the polymers were solubilised with 0.5 and 1.0M NaOH and contained, respectively, 92.1 and 90.7% of glucose derived from starch (IST). The neutral sugar and polymers solubilization profiles showed that weakly bound pectins are present mainly in SPF-Co (water-soluble), CDTA and 0.01-0.1M NaOH soluble fractions. Less soluble, highly cross-linked pectins were solubilised with 4.0M NaOH. This pectin is arabinose-rich, probably highly branched and has a higher molecular weight than the pectin present in SPF-Co, CDTA and 0.01-0.1M NaOH fractions.

Development of an alternative technology for the oyster mushroom production using liquid inoculum

Pleurotus ostreatus, worldwide known as oyster mushroom, was cultivated in banana straw using inocula produced by two different processes - liquid inoculum and the traditionally used solid inoculum. Different ratios (5, 10, 15, and 20%) were tested. Biological efficiency, yield, productivity, organic matter loss, and moisture of fruiting bodies as well as physical-chemical characteristics of banana straw were studied. Significant differences were observed for cellulose, lignin, and hemicellulose content between one and two harvests for both solid and liquid inocula. It was observed that P. ostreatus growth promoted higher degradation of lignin (80.36%), followed by hemicellulose (78.64%) and cellulose (60.37%). Significant differences between one and two harvests were also observed for the production parameters (biological efficiency and yield) for both kinds of inocula, liquid and solid. However, significant differences in productivity between harvests were observed only for solid inoculum.

Effect of addition of different hydrocolloids on pasting, thermal, and rheological properties of cassava starch

Starches and gums are hydrocolloids frequently used in food systems to provide proper texture, moisture, and water mobility. Starch-gum interaction in food systems can change the starch granule swelling and its gelatinization and rheological properties. In this study, the effect of the addition of xanthan gum (XG), sodium carboxymethyl cellulose (SCMC), and carrageenan (CAR) at the concentrations of the 0.15, 0.25, 0.35 and 0.45% (w/v) on the pasting, thermal, and rheological properties of cassava starch was studied. The swelling power (SP) and the scanning electron microscopy (SEM) of the starch gels were also evaluated. The results obtained showed that xanthan gum (XG) had a strong interaction with the cassava starch penetrating between starch granules causing increase in pasting viscosities, SP, storage and loss (G', and G", respectively) modulus and reduction in the setback of the starch; sodium carboxymethyl cellulose (SCMC) greatly increased the pasting viscosities, the SP, and the storage and loss (G', and G", respectively) modulus of the starch-mixtures, mainly due to its greater capacity to hold water and not due to the interaction with cassava starch. Carrageenan (CAR) did not change any of the starch properties since there was no interaction between this gum and cassava starch at the concentrations used.

Postharvest technologies for mangosteen (Garcinia mangostana L.) conservation

The application of technologies to extend the postharvest life of mangosteen fruit was studied and compared to storage at 25 °C/70-75%R.H (25 °C control treatment). The fruits were packed in expanded polystyrene (EPS) trays (5 fruits/tray). Five treatments were carried out at 13 °C/ 90-95% RH: application of carnauba wax coating, lecithin + CMC (carboxymethyl cellulose) coating, 50 µm LDPE (low density polyethylene) film coating, 13 µm PVC (Polyvinyl chloride), and non-coated sample (13 °C control treatment). Physicochemical analyses were performed twice a week. A statistical design was completely randomized with 8 repetitions for each treatment plus the control treatment. The results were submitted to variance analysis, and the averages compared by the Tukey test at 5% probability. Among the quality parameters analyzed, more significant differences were observed for weight loss, texture, and peel moisture content. The results showed that the maximum storage period for mangosteen at 25 °C is two weeks; while storage at13 °C can guarantee the conservation of this fruit for 25 days. Therefore, the treatment at 13 °C/90-95% RH without the use of coatings and films was more effective and economical.

Chemical composition and effects of micronized corn bran on iron bioavailability in rats

The degermination of corn grains by dry milling generates 5% of a fibrous residue. After segregation and micronization, corn bran becomes a potential source of dietary fiber consumption. However, its effect on iron bioavailability has not been reported in the literature. The objective of the present study was to determine the nutritional composition of corn bran and its effects on iron bioavailability using the hemoglobin depletion-repletion method in rats. The animals were divided into two groups: cellulose (control) and corn bran (experimental). The bran had high content of total dietary fiber, especially the insoluble fraction, and low phytate content. Hemoglobin uptake did not differ between groups at the end of repletion period, and the iron relative bioavailability value of the corn bran diet was 104% in comparison to that of the control group. The product evaluated proved to be a potential source of dietary fiber and it showed no negative effects on iron bioavailability.

Optimization and functionality of millet supplemented pasta

Abstract Millets are having superior nutritional qualities and health benefits; hence they can be used for supplementation of pasta. Pasta was prepared using composite flour (CF) of durum wheat semolina (96%) and carrot pomace (4%) supplemented with finger millet flour (FMF, 0-20g), pearl millet flour (PMF, 0-30g) and carboxy methyl cellulose (CMC, 2-4g). Second order polynomial described the effect of FMF, PMF and CMC on lightness, firmness, gruel loss and overall acceptability of extruded pasta products. Results indicate that an increasing proportion of finger and pearl millet flour had signed (p≤0.05) negative effect on lightness, firmness, gruel loss and overall acceptability. However, CMC addition showed significant (p≤0. 05) positive effect on firmness, overall acceptability and negative effect on gruel loss of cooked pasta samples. Numeric optimization results showed that optimum values for extruded pasta were 20g FMF, 12g PMF and 4g CMC per 100g of CF and 34ml water with 0.981 desirability. The pasta developed is nutritionally rich as it contains protein (10.16g), fat (6g), dietary fiber (16.71g), calcium (4.23mg), iron (3.99mg) and zinc (1.682mg) per 100g.

Survey of trace element and dietetic fiber composition of “Leblebi” which is a local snack food consumed in Turkey

Abstract In Turkey and several Middle East countries' people consume “leblebi” which is a traditional snack food made from chickpeas (Cicer arietinum L.). Chickpea products are highly nutritive and a cheap food for human consumption and have become an essential part of daily diets in the world. The present study aims to determine the chemical, nutritional and dietary composition of fifty leblebi samples marketed in Turkey. Protein values of the leblebi ranged from 19.4 to 23.9% dehulled and 20.3 to 20.8% for nondehulled leblebi while a value of 19.1% was recorded for chickpeas. Mineral results showed that Potassium (K) was the most abundant element in leblebi ranging from 6514 to 14431 mg/kg. The amount of dietary components neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and cellulose did not vary much between the samples analyzed.

Pearl millet seed pelleting

The pearl millet seed is small and its size varies, making sowing more difficult. The pelleting technique increases and homogenizes seed size, but it is essential to determine the physical and physiological characteristics of pelleted seeds. The physiological analysis consisted of: first germination count, final germination, speed emergence index, and seedling emergence. Physical analysis consisted of determining the 1000-seed weight, 1000-seed volume and fragmentation. The control treatment did not receive any coating, and the other 36 treatments combined four binders: bentonite, polyvinyl acetate (PVA), polyvinylpyrrolidone (PVP) and methyl cellulose (Methocel®), and nine powder coating products: microcellulose, plaster, vermiculite, magnesium thermophosphate (Yoorin®), phytic acid, dicalcium phosphate, super simple phosphate (SS), monoamonic phosphate (MAP) and reactive phosphate. Among the materials used to form the pearl millet pellet, the most efficient binders were the polyvinyl acetate and the methyl cellulose, and as coaters, the vermiculite and the microcellulose.